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I did a rebuild because of lifter failure. Installed nsr truck norris cam sent ecm to get programed. Because would not idle, upper rpm had good power. After tune idle was great. But, I had a lot of spark knock. Finally broke down and bought tuner, sent a log file and got a couple of re-tunes. Now at least 1 piston failed and threw a rod. Would like to see if you guys think the tune was to blame.Attachment 163247
It's pretty hard to break a piston in an NA engine. Most likely cause is some error in installation. I know that's not what you want to hear but it is reality.
It had really bad spark knock when not under load. Basically right before shift. I know it could have been something I did wrong or didn't catch but the knocking was bad and only not under load.Quote:
Originally Posted by edcmat-l1
Show us the spark plugs, combustion chambers, piston tops and around the ring lands, and the top of the cylinder bores. Basically look for evidence of detonation everywhere it would show it's face. I didn't scour the .hpt file but at first glance the spark tables look reasonable, that's not to say I don't suspect a modifier table or two. Often times the destroyed hole is very difficult to find the culprit if the carnage is massive, but there should be some evidence of knock in at least one other hole if knock is the culprit.
Also know this, the knock sensors are tuned to the original sum of parts. When you change even the smallest of parts, such as valve springs, the frequency of the combination changes and therefore so would the behavior of the knock sensors. Basically, don't trust them until you know you can trust them. Truly being able to trust them is usually a process that most people do not go through.
It would have to be knocking super hard and for a while to hurt anything. So much so that if that's the case.. and I hate to point the blame at you but it's your fault. If you can hear it audibly knocking and don't get out of it and re-adjust... it's kind of on you.
This isn't like a stock bottom end car making 800 rwhp with 15 psi of boost... where one good knock event might trash it.. You'd have to really abuse a NA motor to hurt it.
Spark knock under no-load conditions doesn't really mean anything. To break a piston it has to be under load, knocking, too much timing, not enough fuel, or a combo of both.Quote:
Originally Posted by Karl h
If you put the engine together and did not at least check the piston ring gap, there's your problem. You can easily butt a ring if the gap is too tight to begin with. This is the most likely scenario.
Please post pics of parts